The invention relates generally to a method of manufacturing a randomly patterned floor covering having contrastingly-colored zones from a preform of rubber and, more particularly, to an improved method in which the preform is cut into pieces, which are molded into the shape of blanks having projections extending from the top side thereof in a relief-like fashion, solidified by vulcanization and then machined by cutting only in the region of the projections.
This type of method is disclosed in DE-OS2836642 in which a thick lower layer and a thin upper layer are placed into a forming tool and pressed together. Randomly placed recesses in the forming tool are used to form projections in a relief-like fashion at the side of the blank that eventually is exposed for viewing. The projections are ground off this side after vulcanization in such a manner that the upper flat portion is completely removed at this point and the contrastingly-colored lower flat portion becomes visible. The upper and the lower portions require separate production and processing, which results in considerable costs.
In U.S. Pat. No. 1,816,822, a method for producing a rubber floor covering is disclosed in which contrastingly-colored, vulcanized rubber particles are distributed in an unvulcanized rubber mixture. The ensuing conglomerate mass is subsequently drawn into a sheet after which a semi-curing process, in which the conglomerate mass is partly vulcanized, occurs. Next the upper side of the sheet is sanded or buffed to cut back the outer surface and expose the particles. Finally, the vulcanization process is completed. The contrastingly-colored zones, which are determined by the location of the particles, are related to each other by a statistical distribution. An observer viewing a floor covering made according to this method will receive an overall impression of a speckled or marblized appearance. A floor covering having a pattern of a defined shape cannot be obtained with this method.